This is a Python library to use the GATT Protocol for Bluetooth LE devices. It is a wrapper around the implementation used by gatttool in bluez package. It does not call other binaries to do its job :)
There are many ways of installing this library: using Python Pip, using the Debian package, or manually compiling it.
First, you need to install the depends. In Debian/Ubuntu this will be something like:
sudo apt install pkg-config libboost-python-dev libboost-thread-dev libbluetooth-dev libglib2.0-dev python-dev
Now, install as ever:
pip install gattlib
There is a single Debian package available from https://github.com/oscaracena/pygattlib/releases. Just download it and install using the following command:
sudo apt install ./python3-gattlib*.deb
You should install the needed packages, which are described on DEPENDS
file. Take special care about versions: libbluetooth-dev should be
4.101 or greater. Then, just type:
./setup.py install --user
This library provides two ways of work: sync and async. The Bluetooth LE GATT protocol is asynchronous, so, when you need to read some value, you make a petition, and wait for response. From the perspective of the programmer, when you call a read method, you need to pass it a callback object, and it will return inmediatly. The response will be "injected" on that callback object.
This Python library allows you to call using a callback object (async), or without it (sync). If you does not provide a callback (working sync.), the library internally will create one, and will wait until a response arrives, or a timeout expires. Then, the call will return with the received data.
To discover BLE devices, use the DiscoveryService provided. You need
to create an instance of it, indicating the Bluetooth device you want
to use. Then call the method discover, with a timeout. It will
return a dictionary with the address and name of all devices that
responded the discovery.
Note: it is very likely that you will need admin permissions to do
a discovery, so run this script using sudo (or something similar).
As example:
from gattlib import DiscoveryService
service = DiscoveryService("hci0")
devices = service.discover(2)
for address, name in devices.items():
print("name: {}, address: {}".format(name, address))First of all, you need to create a GATTRequester, passing the address of the device to connect to. Then, you can read a value defined by either by its handle or by its UUID. For example:
from gattlib import GATTRequester
req = GATTRequester("00:11:22:33:44:55")
name = req.read_by_uuid("00002a00-0000-1000-8000-00805f9b34fb")[0]
steps = req.read_by_handle(0x15)[0]The process is almost the same: you need to create a GATTRequester
passing the address of the device to connect to. Then, create a
GATTResponse object, on which receive the response from your
device. This object will be passed to the async method used.
NOTE: It is important to maintain the Python process alive, or the
response will never arrive. You can wait on that response object, or you
can do other things meanwhile.
The following is an example of response waiting:
from gattlib import GATTRequester, GATTResponse
req = GATTRequester("00:11:22:33:44:55")
response = GATTResponse()
req.read_by_handle_async(0x15, response)
while not response.received():
time.sleep(0.1)
steps = response.received()[0]And then, an example that inherits from GATTResponse to be notified when the response arrives:
from gattlib import GATTRequester, GATTResponse
class NotifyYourName(GATTResponse):
def on_response(self, name):
print("your name is: {}".format(name))
response = NotifyYourName()
req = GATTRequester("00:11:22:33:44:55")
req.read_by_handle_async(0x15, response)
while True:
# here, do other interesting things
sleep(1)The process to write data is the same as for read. Create a GATTRequest object,
and use the method write_by_handle to send the data. This method will issue a
write request. As a note, data must be a bytes object. See the following
example:
from gattlib import GATTRequester
req = GATTRequester("00:11:22:33:44:55")
req.write_by_handle(0x10, bytes([14, 4, 56]))You can also use the write_cmd() to send a write command instead. It has the
same parameters as write_by_handle: the handler id and a bytes object. As an
example:
from gattlib import GATTRequester
req = GATTRequester("00:11:22:33:44:55")
req.write_cmd(0x001e, bytes([16, 1, 4]))To receive notifications from remote device, you need to overwrite the
on_notification method of GATTRequester. This method is called
each time a notification arrives, and has two params: the handle where
the notification was produced, and a string with the data that came in
the notification event. The following is a brief example:
from gattlib import GATTRequester
class Requester(GATTRequester):
def on_notification(self, handle, data):
print("- notification on handle: {}\n".format(handle))You can receive indications as well. Just overwrite the method
on_indication of GATTRequester.
This software may harm your device. Use it at your own risk.
THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY
APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT
HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM “AS IS” WITHOUT
WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND
PERFORMANCE OF THE PROGRAM IS WITH YOU. SHOULD THE PROGRAM PROVE
DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING, REPAIR OR
CORRECTION.